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of pollutants emitted. The more toxic a substance is, the higher is the increase in
DALY.
From the results using the endpoint indicators derived in this study on the one
hand, and the HTP on the other hand, it seems that the HTP concept underestimates
the environmental importance of transport. Although the share of transport in Sce-
nario 1 is 2.1/1.7% for HTP (CML/EDIP), it is between 3.2 and 4.2% for the endpoint
indicators derived in this study. Although the share of transport for the endpoint
indicators reaches between 17.1 and 19.6% in Scenario 2, the share for HTP is still
quite small (12.0/5.8%). However, the CML approach is closer to the results obtained
by the endpoint approach than the EDIP approach. The gap widens even more in
Scenario 3: (35.5/20.7%) for HTP and 44.1 to 49.2% for the endpoint indicators,
respectively.
The reason for the differences between the results for the HTP and the endpoint
indicators is clear. The studied HTP methods consider the fate of the substances,
but do not include exposure information. The environmental impact of transport is
highly dependent on the location where it takes place, so the deviation from the
HTP results is obvious. The results using the impact indicators of this study, however,
show the limits of the ecological benefits of a further technical improvement of the
flue gas cleaning. Scenario 3 indicates a clear overall reduction; however, it shows
also that nearly half of the overall environmental impact is due to transport. There-
fore, further technical improvement at the waste incinerator should only be carried
out if transport does not increase significantly, which would worsen the overall
environmental efficiency of the process chain.
It has been found that the chosen HTP methods underestimate transport in this
case study and, therefore, does not identify very well the differences in the environ-
mental impact for the two different processes considered. Figure 7.9 shows the
results for all three cases — differentiated in waste incinerator and transport — for
the population exposure, DALY (egalitarian) and HTP (EDIP).
The HTP indicators may be misleading in the comparison of the absolute envi-
ronmental burden as well. For instance, if significant reductions only happen in
regions with a low population density and high wind speeds (the factors that account
for a low population exposure), the reduction for the endpoint indicators derived in
this study will be rather small, while the HTP indicators will identify significant
reductions. It can therefore be concluded that the use of endpoint indicators as
derived in this study is beneficial with respect to a gain of information for both
purposes: the comparison of different scenarios and the comparison of different
processes within one scenario.

7.7.7 UNCERTAINTIES IN THE APPLIED FRAMEWORK
Essential for the validity of the presented application of site-dependent impact
assessment is the question of whether the uncertainties introduced are justified by
the gain of information in comparison to the traditional impact potential used in
LCIA. In this context, it must be highlighted that the methodology described in this
chapter should be seen as a balance between the uncertainties introduced on the one
hand and the handiness and feasibility of the applied method on the other. In general,

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